Dynamic meta_query WP_Query

<?php

if ( ( $_GET["var1"] != '' ) || ( $_GET["var2"] != '' ) || ( $_GET["var3"] != '' ) ) {

	if ( $_GET["var1"] != '' ) {
		$meta_query[] = array( 'key' => 'meta_value1', 'value' => $_GET["var1"], 'compare' => '=' );
	}
	
	if ( $_GET["var2"] != '' ) {
		$meta_query[] = array( 'key' => 'meta_value2', 'value' => $_GET["var2"], 'compare' => '=' );
	}

	if ( $_GET["var3"] != '' ) {
		$meta_query[] = array( 'key' => 'meta_value3', 'value' => $_GET["var3"], 'compare' => '=' );
	}
	
	$args = array (
		'post_type'     => 'cpt_type',
		'meta_query'	=> $meta_query
	);

} else {
	$args = array (
	        'post_type'     => 'cpt_type'
	);
}

?>