Use OR filter for metrics in the Facebook Ads API

Question

I'm trying to use an OR filter in the Facebook Ads API. I want to fetch all campaigns that has impressions > 0 OR spend > 0. According to the Facebook Ads API documentation you can use "Formula fields" to set arithmetic expressions as a field, so I figured that I could fetch campaigns with "impressions + cost" as a field.

With the below code I get the following error: "Filtering field 'impressions + spend' is not supported". Using only e.g. "impressions" works fine. I tried examples from the documentation like: "0.8 * cpc", but got the same error.

Do anybody know how Formula Fields in the Facebook API should be used?

$fields = [CampaignFields::OBJECTIVE, CampaignFields::ID, CampaignFields::STATUS, CampaignFields::NAME];
$params = [
        'limit' => PHP_INT_MAX,
        CampaignFields::EFFECTIVE_STATUS => [CampaignEffectiveStatusValues::ACTIVE],
        'filtering' => [['field' => 'impressions + spend', 'operator' => InsightsOperators::GREATER_THAN, 'value' => 0]],
        'date_preset' => InsightsResultDatePresetValues::YESTERDAY,];