guzzle-file.php

<?php
        $client = new Client();
        try {
            $response = $client->request('POST', $uri, [
                'headers' => ['Accept' => 'application/json',  'Content-type' => 'application/json', 'Authorization' => $apikey],
                ['body'=>json_encode($myBody)],
                'multipart' => [
                    [
                        'Content-type' => 'multipart/form-data',
                        'name' => 'file',
                        'contents' => $file,
                        'filename' => 'filename.jpg',

                    ]

                ],
                ]);
        }
        catch (ClientException $e){
            return $e->getMessage();
        }