Is there a way to get metabox information within the args?

Hello,
I am back again because what I thought might be a solution is not fruitful. So, my question is: Is there a way to filter what posts are in my loop based on the arguments of the wp_query? I see there is a way of getting meta information with meta_query:

$meta_query_args = array(
'relation' => 'OR', // Optional, defaults to "AND"
array(
'key' => '_my_custom_key',
'value' => 'Value I am looking for',
'compare' => '='
)
);
$meta_query = new WP_Meta_Query( $meta_query_args );

Thoughts? I can show a larger snippet of my code if it's needed for my question to have some context.