How I can change the condition or compare operator for WP_Query in pre_get_posts

So here is my problem I want to show Posts if have same category if not have post then show post of same tag. And to do that I am using "pre_get_posts" action. and setting query like following.

function related_custom_posts($  query){    $  query->set( 'category__in', array(2,3) );    $  query->set( 'tag__in', array(10,13) ); }  add_action( 'pre_get_posts', 'related_custom_posts', 1 ); 

But it create sql like this AND ( wp_term_relationships.term_taxonomy_id IN (2) AND tt1.term_taxonomy_id IN (11) ) but i need this with OR condition AND ( wp_term_relationships.term_taxonomy_id IN (2) OR tt1.term_taxonomy_id IN (11) )

Thanks in advance.