全角も半角も検索するには？

こんにちは

検索条件で、照合順序(collation)を utf8_unicode_ci にすればよさそうです。
下記のページで、MySQL の照合順序について詳しく解説されています。
http://qiita.com/Vit-Symty/items/159c27d7d62c78ee9ce7

例）

function my_posts_search( $search, $wp_query ) {
	global $wpdb;

	if ( ! $wp_query->is_search )
		return;

	$search = '';

	$q = $wp_query->query_vars;
	$n = ! empty( $q['exact'] ) ? '' : '%';
	$exclusion_prefix = apply_filters( 'wp_query_search_exclusion_prefix', '-' );

	foreach ( $q['search_terms'] as $term ) {
		$exclude = $exclusion_prefix && ( $exclusion_prefix === substr( $term, 0, 1 ) );
		if ( $exclude ) {
			$like_op  = 'collate utf8_unicode_ci NOT LIKE';
			$andor_op = 'AND';
			$term     = substr( $term, 1 );
		} else {
			$like_op  = 'collate utf8_unicode_ci LIKE';
			$andor_op = 'OR';
		}

		if ( $n && ! $exclude ) {
			$like = '%' . $wpdb->esc_like( $term ) . '%';
			$q['search_orderby_title'][] = $wpdb->prepare( "{$wpdb->posts}.post_title LIKE %s", $like );
		}

		$like = $n . $wpdb->esc_like( $term ) . $n;
		$search .= $wpdb->prepare( "{$searchand}(({$wpdb->posts}.post_title $like_op %s) $andor_op ({$wpdb->posts}.post_excerpt $like_op %s) $andor_op ({$wpdb->posts}.post_content $like_op %s))", $like, $like, $like );
		$searchand = ' AND ';
	}

	if ( ! empty( $search ) ) {
		$search = " AND ({$search}) ";
		if ( ! is_user_logged_in() ) {
			$search .= " AND ({$wpdb->posts}.post_password = '') ";
		}
	}

	return $search;
}
add_filter('posts_search','my_posts_search', 10, 2);