Dynamic ads on Search Results page

This is a business directory website.

How can I display ads based on the posts category displayed in the search results?

When a user visits say the Automotive page automotive ads are displayed in the sidebar and this works perfectly.

BUT… when I do a search for say Automotive the sidebar shows nothing. I would like it to work as the normal posts do. In the url of the search page I see ?sq= which I assume I need to prepend to the args in my loop but I’m not sure how. I may even be completely wrong.

Here is what my loop looks like inside the page-search.php file

$args = array(
	'post_type' => 'cn_ad',
	'posts_per_page' => get_option( 'posts_per_page' ),
	'orderby' => 'date',
	'order' => 'DESC',
	'tax_query' => array(
		array(
			'taxonomy' => 'category',
			'field' => 'id',
			'terms' => get_query_var( 'cat' ),
			),
		),
	);
	query_posts( $args ); ?>

		<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

		<?php if ( has_post_thumbnail() ) { // check if the post has a Post Thumbnail assigned to it.
		  the_post_thumbnail('medium', array('class' => 'thumbnail'));
		}
		?>

		<?php endwhile; ?>

		<?php else : ?>

		<?php // TODO: do something else ?>

		<?php endif; ?>