function wpse21352_template_part_cb( $slug )
{
    if(slug == 'user_menu') {
         return WP_PLUGIN_URL.'/'.$slug;
    } else {
         return $slug;
    }
}

do_action( "get_template_part_user_menu", 'user_menu' );
add_action( 'wpse21352_template_part_cb', 'get_template_part_user_menu', 10, 1 );

$themePartSlug = apply_filters('ppr_one_search_item_view');

// Template file from plugin Directory

load_template(PPR1_PLUGIN_PATH.'templates/search_places.php');