Exclude posts with a custom meta value from search

exclude_posts_with_meta.php

<?php
/**
 * Exclude posts with 'fruit' custom meta field value of 'bananas' from site Search
 */
function cc_search_filter( $query ) {
	if ( ! is_admin() && $query->is_main_query() ) {
		if ( $query->is_search ) {
			$query->set( 'meta_query',
				array(
					'relation' => 'OR',
					array(
						'key' => 'fruit',
						'value' => 'Banana',
						'compare' => '!=',
					),
					array(
						'key' => 'fruit',
						'compare' => 'NOT EXISTS',
					),
				)
			);
		}
	}
}
add_action( 'pre_get_posts', 'cc_search_filter' );