I will show you different examples of how you can order your posts by meta values. First of all, look at this simple code sample, where we don’t even use meta query:

$args = array(
	'meta_key' => 'misha_key',
	'orderby' => 'meta_value'
);

Now, let’s say that misha_key contains only numeric values, we can change our code for that case just a little bit.

$args = array(
	'meta_key' => 'misha_key',
	'orderby' => 'meta_value_num'
);

But how to use it together with meta query? Simple, just change our code the following way:

$args = array(
	'meta_query' => array(
		'misha_clause' => array(
			'key' => 'misha_key',
			'compare' => 'EXIST'
		)
	),
	'orderby' => 'misha_clause'
);

How to Order by Two and More Meta Keys

Yes, it is also possible since WordPress 4.2

$args = array(
	'meta_query' => array(
		'relation' => 'AND',
		'price_clause' => array(
			'key' => 'price',
			'value' => array( 2000, 4000 ),
			'type' => 'numeric',
			'compare' => 'BETWEEN'
		),
		'misha_clause' => array(
			'key' => 'misha_key',
			'compare' => 'EXISTS'
		), 
	),
	'orderby' => array(
		'price_clause' => 'ASC',
		'misha_clause' => 'DESC'
	),
);