BuddyPress.org

You can enable search for names by putting this code in your child themes functions.php:

add_filter( 'bp_activity_get_include_user_search', 'venutius_add_name_to_search' );

function venutius_add_name_to_search( $setting ) {
	return true;
}

Unfortunately there’s not a similar filter for the title, you could raise a feature request for this on https://buddypress.trac.wordpress.org/