order wordpress posts using url variables

search.php

//passing variables like ?orderby=title


$my_query = new WP_Query( array( 
    'post_type' => 'project',
    'post_status' => 'publish',
    'orderby' => get_query_var('orderby'), // will return orderby query string variable
    'order' => 'DESC', 
    'paged' => get_query_var('paged'),
));