How to order posts list using wp_query? - wordpress

Question

I want to order my list with wp_query. I have posts with meta_key 'featured_post' and three values for that key for different posts it is: '1', '2', and thrird key not exist.
I am using now this wp_query structure:
global $paged, $wp_query, $wp;
$args = wp_parse_args($wp->matched_query);
if ( !empty ( $args['paged'] ) && 0 == $paged ) {
$wp_query->set('paged', $args['paged']);
$paged = $args['paged'];
}
$temp = $wp_query;
$args = array(
'post_type' => 'post',
'post_status' => 'publish',
'posts_per_page' => 20,
'paged' => $paged,
'meta_query' => array(
'relation' => 'OR',
'featured_clause_first' => array(
'key' => 'featured_post',
'value' => '1',
'compare' => '='
),
'featured_clause_second' => array(
'key' => 'featured_post',
'value' => '2',
'compare' => '='
),
'featured_clause_third' => array(
'key' => 'featured_post',
'compare' => 'NOT EXISTS',
'value' => '1'
)
),
'orderby' => array(
'featured_clause_first' => 'DESC',
'featured_clause_second' => 'DESC',
'featured_clause_third' => 'DESC'
),
);
$wp_query = null;
$wp_query = new WP_Query($args);
while ($wp_query->have_posts()) : $wp_query->the_post();
get_template_part( 'templates/single');
endwhile;
wp_reset_postdata();
wp_reset_query();
But I am got wrong order. Finally I need to see posts with value '1' at the top and other posts with values '2' and not exist key after.
Note: I can't use "'meta_key' => 'featured_post'," because in this way posts without existing meta_key not displayed.

Answer 1

Ok. I was edited save metabox functions for delete metakey if featured not checked. So that I have only two values: 1 & key not exist. After that I got needed order with this meta args:
$sort_meta_query = array(
'relation' => 'OR',
'featured_clause' => array(
'key' => 'featured_post',
'value' => '1',
'compare' => '='
),
array(
'key' => 'featured_post',
'compare' => 'NOT EXISTS',
'value' => '1'
)
);
$sort = array(
'orderby' => array(
'featured_clause' => 'DESC',
'date' => 'DESC'
)
);