I found something. I hope it helps you. Maybe you can modify and use it
$('#btnUpdateReport').click(function () {
// add the parameters to the controller parameters
var pId = $('#txtPortfolioId').val();
var viewer = $reportViewer.data('telerik_ReportViewer');
viewer.reportSource($.extend({}, viewer.reportSource(), { parameters: { 'portfolioId': pId } }));
});
http://www.telerik.com/forums/external-report-viewer-parameters