Can you try by this way, I think this will solve your problem
$collection->getSelect()
->where(" (IF('Your`Your attribute')attribute` LIKE= 'Value') AND (IF('Your`Your attribute')attribute` LIKE= 'Value'))
OR
((IF('Your`Your attribute')attribute` LIKE= 'Value') AND `Your attribute` = 'Value')");
In your case in the getSelect() could be:
->getSelect(IF)->where('Your"(`supplier_id` attribute'= '1' AND `product_type` = 'first_type') LIKEOR 'Value'(`supplier_id` = '2' AND `product_type` = 'another_type')");