diff --git a/.gitignore b/.gitignore
index c527c3a..bff2d16 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,6 +10,8 @@ vendor/
 # Environment files
 .env/*.*
 
+# Docker compose env file
+.env
 # Local configs
 .php_cs
 .php_cs.cache
diff --git a/README.md b/README.md
index a3868b2..d1df90d 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ All updates to this library are documented in our [CHANGELOG](CHANGELOG.md).
 - [Installation](#installation)
 - [Quick Start](#quick-start)
 - [Usage](#usage)
+- [Docker](#docker)
 - [How to Contribute](#contribute)
 - [Thanks](#thanks)
 - [About](#about)
@@ -155,6 +156,44 @@ with message from CURL on why the request failed. Use the message as a hit to tr
 
 - [Usage Examples](USAGE.md)
 
+<a name="docker"></a>
+# Docker
+
+This repo comes with a `docker-compose.yml` file to get a development environment up and running quickly.
+
+## Prerequisites
+
+- Install [Docker](https://www.docker.com/) on your local machine.
+
+## Instructions
+
+Clone this repo to your local machine.
+
+```
+$ git clone https://github.com/sendgrid/php-http-client.git
+```
+
+Create a .env file at the root of the repo and add your API key.
+
+```
+$ cd php-http-client
+$ echo "SENDGRID_API_KEY='YOUR_API_KEY'" >> .env
+```
+
+Create the containers.
+
+```
+$ docker-compose up -d
+```
+
+The `examples` directory is now available locally by visiting `localhost:8080`. Run the provided `example.php` file by clicking on the link in the browser or experiment with your own files by adding them to the `examples` folder.
+
+Destroy the containers.
+
+```
+$ docker-compose down
+```
+
 ## Environment Variables
 
 You can do the following to create a .env file:
diff --git a/docker-compose.yml b/docker-compose.yml
new file mode 100644
index 0000000..d301541
--- /dev/null
+++ b/docker-compose.yml
@@ -0,0 +1,19 @@
+version: '3'
+services:
+  nginx:
+    image: nginx:latest
+    container_name: php-http-client-nginx
+    ports:
+      - "8080:80"
+    volumes:
+      - ./:/php-http-client
+      - ./docker/files/default.conf:/etc/nginx/conf.d/default.conf
+    links:
+      - php
+  php:
+    image: php:7-fpm
+    container_name: php-http-client-php-fpm
+    volumes:
+      - ./:/php-http-client
+    environment:
+      SENDGRID_API_KEY: ${SENDGRID_API_KEY}
diff --git a/docker/files/default.conf b/docker/files/default.conf
new file mode 100644
index 0000000..c2ea241
--- /dev/null
+++ b/docker/files/default.conf
@@ -0,0 +1,23 @@
+server {
+    listen 80;
+    server_name localhost;
+
+    root /php-http-client/examples;
+
+    access_log /var/log/nginx/access.log;
+    error_log  /var/log/nginx/error.log;
+
+    location / {
+        autoindex on;
+    }
+
+    location ~ \.php$ {
+        try_files $uri =404;
+        fastcgi_split_path_info ^(.+\.php)(/.+)$;
+        fastcgi_pass php:9000;
+        fastcgi_index index.php;
+        include fastcgi_params;
+        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
+        fastcgi_param PATH_INFO $fastcgi_path_info;
+    }
+}
diff --git a/examples/example.php b/examples/example.php
index 107d95a..849aeb7 100644
--- a/examples/example.php
+++ b/examples/example.php
@@ -15,47 +15,78 @@
 $queryParams = ['limit' => 100, 'offset' => 0];
 $requestHeaders = ['X-Mock: 200'];
 $response = $client->api_keys()->get(null, $queryParams, $requestHeaders);
-echo $response->statusCode();
-echo $response->body();
-echo $response->headers();
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
 
 // GET /v3/api_keys - retrieve all API Keys that belong to the user
 $queryParams = ['limit' => 100, 'offset' => 0];
 $requestHeaders = ['X-Mock: 200'];
 $retryOnLimit = true; // with auto retry on rate limit
 $response = $client->api_keys()->get(null, $queryParams, $requestHeaders, $retryOnLimit);
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
 
 // POST /v3/api_keys - create a new user API Key
 $requestBody = [
     'name' => 'My PHP API Key',
     'scopes' => [
+        'api_keys.create',
+        'api_keys.delete',
+        'api_keys.read',
+        'api_keys.update',
         'mail.send',
         'alerts.create',
-        'alerts.read'
+        'alerts.read',
     ]
 ];
 $response = $client->api_keys()->post($requestBody);
 $responseBody = json_decode($response->body(), true);
 $apiKeyId = $responseBody['api_key_id'];
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
 
 // GET /v3/api_keys/{api_key_id} - retrieve a single API Key
 $response = $client->api_keys()->_($apiKeyId)->get();
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
 
 // PATCH /v3/api_keys/{api_key_id} - update the name of an existing API Key
 $requestBody = [
     'name' => 'A New Hope'
 ];
 $response = $client->api_keys()->_($apiKeyId)->patch($requestBody);
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
 
 // PUT /v3/api_keys/{api_key_id} - update the name and scopes of a given API Key
 $requestBody = [
     'name' => 'A New Hope',
     'scopes' => [
-        'user.profile.read',
-        'user.profile.update'
+        'api_keys.create',
+        'api_keys.delete',
+        'api_keys.read',
+        'api_keys.update',
     ]
 ];
 $response = $client->api_keys()->_($apiKeyId)->put($requestBody);
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
 
 // DELETE /v3/api_keys/{api_key_id} - revoke an existing API Key
 $response = $client->api_keys()->_($apiKeyId)->delete();
+var_dump($response->statusCode());
+var_dump($response->body());
+// var_dump($response->headers());
+echo '<br><br>';
diff --git a/lib/Client.php b/lib/Client.php
index b15595c..6ab545d 100644
--- a/lib/Client.php
+++ b/lib/Client.php
@@ -370,7 +370,8 @@ private function buildUrl($queryParams = null)
      */
     private function createCurlOptions($method, $body = null, $headers = null)
     {
-        $options = [
+        $options = array_replace(
+            [
                 CURLOPT_RETURNTRANSFER => true,
                 CURLOPT_HEADER => true,
                 CURLOPT_CUSTOMREQUEST => strtoupper($method),
@@ -378,18 +379,24 @@ private function createCurlOptions($method, $body = null, $headers = null)
                 CURLOPT_FAILONERROR => false,
             ] + $this->curlOptions;
 
+        $requestHeaders = ['Content-Type: application/json'];
+
+        // Merge client headers
+        if (isset($this->headers)) {
+            $requestHeaders = array_merge($requestHeaders, $this->headers);
+        }
+
+        // Merge request headers
         if (isset($headers)) {
-            $headers = array_merge($this->headers, $headers);
-        } else {
-            $headers = $this->headers;
+            $requestHeaders = array_merge($requestHeaders, $headers);
         }
 
         if (isset($body)) {
             $encodedBody = json_encode($body);
             $options[CURLOPT_POSTFIELDS] = $encodedBody;
-            $headers = array_merge($headers, ['Content-Type: application/json']);
         }
-        $options[CURLOPT_HTTPHEADER] = $headers;
+
+        $options[CURLOPT_HTTPHEADER] = $requestHeaders;
 
         if (class_exists('\\Composer\\CaBundle\\CaBundle') && method_exists('\\Composer\\CaBundle\\CaBundle', 'getSystemCaRootBundlePath')) {
             $caPathOrFile = \Composer\CaBundle\CaBundle::getSystemCaRootBundlePath();