pagination hook doesn’t work with search results

I use my custom Pagination function on my web site;

#Pagination 
    function pagination($prev = '«', $next = '»') {
        global $wp_query, $wp_rewrite;
            $wp_query->query_vars['paged'] > 1 ? $current = $wp_query->query_vars['paged'] : $current = 1;
            $pagination = array(
                'base' => @add_query_arg('paged','%#%'),
                'format' => '',
                'total' => $wp_query->max_num_pages,
                'current' => $current,
                'prev_text' => __($prev),
                'next_text' => __($next),
                'type' => 'plain'
            );
        if( $wp_rewrite->using_permalinks() )
        $pagination['base'] = user_trailingslashit( trailingslashit( remove_query_arg( 's', get_pagenum_link( 1 ) ) ) . 'sayfa/%#%/', 'paged' );
                if( !empty($wp_query->query_vars['s']) )
                    $pagination['add_args'] = array( 's' => get_query_var( 's' ) );

                echo paginate_links( $pagination );
        };

Also i use search by title custom hook;

#Search Just in Title.
function __search_by_title_only( $search, &$wp_query ) {
    global $wpdb;

    if ( empty( $search ) )
        return $search; // skip processing - no search term in query

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

    $search =
    $searchand = '';

    foreach ( (array) $q['search_terms'] as $term ) {
        $term = esc_sql( like_escape( $term ) );
        $search .= "{$searchand}($wpdb->posts.post_title LIKE '{$n}{$term}{$n}')";
        $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', '__search_by_title_only', 500, 2 );

But whenever you call search results page ;

For example “wordpress tema“(search results for wordpress tema) the pagination hook doesn’t work. Please check the link also you can find some functions on SE here, for search results page .

I think problem is about my second hook:

What is wrong with this ? What should we do? Thanks any help.