is there a way to add extra parameters to query string?

I have tried to add an extra value to the query string on submit.
Purpose is to pass through information that was already in de query string for other reasons.

In the search form for example you can do this
function search_form_alter_submit($form, &$form_state) {
$path = $form_state['redirect'];
$options = array(
'query' => array(
'partner' =>$partner,
)
);
drupal_goto($path, $options);
}

Is there a solution for exposed filters by which I can achieve the same result?
Thanks in advance for any help on this!

Ellis