Okay, so here is the complete query for displaying popular posts of current week. I am using meta_query to limit query results within current week only.
It will get all posts from current week and then sort them by post views count added by custom field wpb_post_views_count that you used in your question.
// Current week's popular posts
$query_args = array(
'post_type' => 'post',
'date_query' => array(
array(
'year' => date( 'Y' ),
'week' => date( 'W' ),
),
),
'meta_key' => 'wpb_post_views_count',
'orderby' => 'meta_value_num',
'ignore_sticky_posts' => 1,
'posts_per_page' => '-1',
);
$my_query = new WP_Query( $query_args );
if ( $my_query->have_posts() ) :
while ( $my_query->have_posts() ) : $my_query->the_post();
// add your loop content here.
endwhile;
endif;
wp_reset_postdata();