so what your saying is $_GET[‘restaurant_assets’] is an array? If so
what you need to do is create a nested meta query with a value for each value in $_GET[‘restaurant_assets’]
$meta_query = array('relation' => 'OR');
foreach ($_GET['restaurant_assets'] as $value) {
$meta_query[] = array(
'key' => 'restaurant_assets',
'value' => '"'.$value.'"',
'compare' => 'LIKE'
}
$args = array(
'numberposts' => -1,
'post_type' => 'restaurant',
'meta_query' => $meta_query
);