Geoserver Cross-layer filter in OpenLayers 2 for WFS protocol

Question

I need to execute a spatial INTERSECTS query between layers of type Point and Polygon, to find points that intersect with a polygon of attribute fclass == park.

CQL Query:

INTERSECTS(geom, collectGeometries(queryCollection('namespace_new:gis.osm_landuse_a_free_1', 'geom','fclass =  park''')))";

I have defined a Vector layer and use WFS protocol to get data from Geoserver:

 var layerDomainData = new OpenLayers.Layer.Vector("Tourist locations", {
           // minScale: 15000000,
            strategies: [new OpenLayers.Strategy.BBOX()],
            protocol: new OpenLayers.Protocol.WFS({
                url: "http://localhost:8080/geoserver/wfs",
                featureType: "tour_data",
                featureNS: "http://localhost:8080/geoserver/namespace_new",
                geometryName: "geom",
                srsName: "EPSG:900913",
                version: "1.1.0"
            }),
                styleMap: new OpenLayers.StyleMap({
          'default' : domainStyle,
          'select' : selectedDomainStyle
        }),
            renderers: renderer            
        });

Usually, I set spatial filters like:

 layerDomainData.filter = new OpenLayers.Filter.Spatial({
    type: OpenLayers.Filter.Spatial.DWITHIN,
    property: "geom",
    value: lineString, //selected feature on the map
    distance: radius,
    distanceUnits: "kilometers",
    projection: "EPSG:4326"
});

but now i have to use Geoservers collectGeometries and queryCollection to select all the features from 'second' layer to intersect with my 'first' layer. If it was a WMS layer I would just set filter as a param (layer.params['CQL_FILTER'] = "filter_string"), but I don't know where to set the required filter when using WFS layer. Didn't find any example of using OpenLayers WFS with Geoserver cross-layer flters.

Any suggestions would be helpful.