var sUrl = "/sap/opu/odata/SAP/ZAPP12_SRV";
var odataModel = new sap.ui.model.odata.v2.ODataModel(sUrl, {
                json: true,
                loadMetadataAsync: true
            });

            var oModel = new sap.ui.model.json.JSONModel();

            odataModel.setHeaders({
                "myCustomparam1": "userPressed",
                "myCustomparam2": new Date(Date.now())
            });