custom query order random

I have the following query but would like to add “orderby random” to it. However it doesn’t work when you do this. Any ideas or help would be much appreciated.

<?php
$args = array(
‘post_type’ => ‘product’,
‘product_cat’ => ‘extras’,
‘product_tag’ => ‘featured-shop’,
‘posts_per_page’ => -1,
);
$loop = new WP_Query( $args );
while ( $loop->have_posts() ) : $loop->the_post(); ?>