$productCollection->addAttributeToFilter(array(
            array('attribute' => 'example_attr_1', 'finset' => $websiteFilter),
            array('attribute' => 'example_attr_2', 'finset' => $websiteFilter)
        ));

$collectionClone = clone $productCollection;
$collectionClone->clear();
$collectionClone->setPageSize(false);