I know the original question has been answered before, but if you want to add OR condition to a simple field to a flat collection, this is the correct way to do it:
'lteq' => date('Y-m-d H:m:i')
'null' => true
This is what I do to filter a count column in a custom grid:
// in the collection class
public function addProductCount()
$innerSelect = $this->getConnection()->select()
['inner_items' => $this->getTable('custom/product')],
['prerequisite_id', 'cnt' => new Zend_Db_Expr('COUNT(inner_items....
Got the solution
Created admin theme and override the filters.html
removed $collapsible.opened() function from file. so the filter will always appear
css="_active: hasVisible() && $collapsible.opened()"