composer.json

{
    "require": {
        "guzzlehttp/guzzle": "4.1.*@dev",
        "guzzlehttp/streams": "dev-master"
    }
}

guzzle4streamhandle_sample.php

<?php
use GuzzleHttp\Adapter\StreamAdapter;
use GuzzleHttp\Message\MessageFactory;

require_once __DIR__.'/vendor/autoload.php';
$config = [
    'adapter' => new StreamAdapter(new MessageFactory)
];

$client = new GuzzleHttp\Client();

$r = $client->get('http://example.com');
$stream = $r->getBody()->detach();
fseek($stream, 0, SEEK_SET);
stream_copy_to_stream($stream, STDOUT);