Order by ABS

Currently I am sorting my posts based on custom_field (that is a number).

However, If I have a posts that have numbers 3 and 12, then the code below sorts is 12,3. How do I sort by number?

I read you can do it bu using ORDER BY ABS, but I dont know how to implement it in my code below.

global $paged;
$curpage = $paged ? $paged : 1;
$args = array('post_type' => 'biznese',
        'paged' => $curpage,
  	'meta_query' => $metaquery,
	'posts_per_page' => 12,
	'meta_key'=>'renditja',
 	'orderby' => 'meta_value',
	'order' => 'asc'
);