Get different kind of entries relatedTo one asset (many to one)?
OK in fact it was very simple: criteria params accept arrays...  

        $criteria = craft()-&gt;elements-&gt;getCriteria(ElementType::Entry);

        $fields = [
            'articleBody.efficyDocuments',
            'efficyDocuments'
        ];

        $criteria-&gt;relatedTo = array(
            'targetElement' =&gt; $asset-&gt;id,
            'field' =&gt; $fields,
        );