order by multiple meta_keys?

This line is wrong:

'meta_key' => 'adminscore' + 'user_like' + '_count-views_all' + 'comment_count',

'meta_key' only accepts string value.

What you need is an additional meta key, e.g. “totalscore” that holds the total value of the scores you have for all the meta values. You can manually run a php function that calculates and store the totalscore value from time to time or use wp_schedule_event to run the function on a set interval.

You can then write the $args as such:

$args = array(
            'meta_key' => 'totalscore',
            'numberposts' => $number_posts,
            'post_status' => $post_status,
            'post_type' => $custom_post_type,
            'orderby' => 'meta_value_num'
);