order by 2 meta field

Hello, i have problem, please can you help me?

I have field meta key (sort_custom), i need first sort by my field, then order popularity (total_sales)

my code

$args = array(

		'orderby'  => array( 
			'meta_value_num' => 'ASC', 
			'total_sales' => 'DESC' 
			),
		'meta_key' => 'sort_custom'

		);

it’s doesn’t work!
if i use “date/title” instead “total_sales, it’s work, but i need work my_field(meta_key) + total_sales, need
first order my field then sort total_sales