How to set request headers in WordPress Rest API calls

Hi am new to WP development, I would like to add request headers to WordPress Rest API calls but don't know how, can anyone help me in this?

I tried following code but no luck

$args = array( 'headers' => array( 'Authorization' => 'Basic ' . base64_encode( Fk-Affiliate-Id . ':' . YOUR_PASSWORD ) ) );

    $api_url = 'http://ift.tt/1Q4a6KB';
    global $affiliate;
    $response = wp_remote_request( add_query_arg( array(
        'Affiliate-Id' => $affiliate['aff-id'],
        'Affiliate-Token'     => $affiliate['aff-token']
    ), $api_url ) , array( 'timeout' => 10));

via Chebli Mohamed