How to create a loop inside WP_Query?

Just construct what you need outside of the main query.

// terms to search
$meta_query_keys = array('Panera Group 2 Encino', 'West Hollywood');

// start the meta query off
$meta_query = array('relation' => 'OR');

// add terms to query
foreach($meta_query_keys as $key) {
    $meta_query[] = array(
        'key'     => 'user_group_name',
        'value'   => $key,
        'compare' => 'LIKE',
    );
}

// construct main query
$wp_user_query = new WP_User_Query(
    array('role'       => 'Subscriber',
          'fields'     => 'all',
          'meta_query' => $meta_query,
    ));