Prioritizing wp_query by meta key - wordpress

Question

I have two custom fields for views. weekly_views and all_views. The weekly views custom field is deleted every week and starts counting views again from 0. So now what I want to achieve is show 12 posts by weekly views but when the custom field is deleted and unless there are views on those posts the query shows nothing. I want to show here posts by all_views instead of no posts.
My query goes as follows but it's not working as I want. In short what I want to achieve is to show posts by weekly_views custom field but if there's no post then show posts by all_views. And also if there's less than 12 posts by weekly_views then show weekly_views posts first and then remaining posts by all_views.
$args = array(
'post_type' => array( 'custom_post_type_1', 'custom_post_type_2'),
'posts_per_page' => '12',
'orderby' => 'meta_value_num',
'order' => 'DESC',
'meta_query' => array(
'relation' => 'OR',
array(
'key' => 'weekly_views',
),
array(
'key' => 'all_views',
),
),
);
The above code is returning me posts but are sorted by all_views.
Edit
The new query that's working for me
<?php
$args = array(
'post_type'=> array( 'custom_post_type1', 'custom_post_type2'),
'posts_per_page' => '12',
'meta_key' => 'weekly_views',
'orderby' => 'meta_value_num',
'order' => 'DESC',
);
$the_query = new WP_Query( $args );
if ($the_query->post_count < 12) {
$countweeklyposts = $the_query->post_count;
$showallpostscount = 12 - $countweeklyposts;
$args2 = array(
'post_type'=> array( 'band', 'artist'),
'posts_per_page' => $showallpostscount,
'meta_key' => 'all_views',
'orderby' => 'meta_value_num',
'order' => 'DESC',
);
$the_query2 = new WP_Query( $args2 );
}
?>
<?php while ($the_query -> have_posts()) : $the_query -> the_post(); ?>
//Code to show posts goes here
<?php
endwhile;
wp_reset_postdata();
?>
<?php while ($the_query2 -> have_posts()) : $the_query2 -> the_post(); ?>
//Code to show posts goes here
<?php
endwhile;
wp_reset_postdata();
?>

Answer 1

You could do this too if you want a little less code
<?php
$args = array(
'post_type'=> array( 'custom_post_type1', 'custom_post_type2'),
'posts_per_page' => '12',
'meta_key' => 'weekly_views',
'orderby' => 'meta_value_num',
'order' => 'DESC',
);
$args2 = array(
'post_type'=> array( 'band', 'artist'),
'posts_per_page' => '12',
'meta_key' => 'all_views',
'orderby' => 'meta_value_num',
'order' => 'DESC',
);
if ($query->post_count > 12) {
$query_args = $args;
}else if($query->post_count < 12){
$query_args = $args2;
}
$query = new WP_Query( $query_args );
while ($query -> have_posts()) : $query -> the_post();
//Code to show posts goes here
endwhile;
wp_reset_postdata();
?>