How chould i get title where "Title characters contains input box then get the values"

i am trying to get the title if it contains the characters in an input box So first if the user types ABC, then get the titles that contains A,B or C

 $("#subSiteTitle").keypress(function () {
    var checkTextTypedIn = $('#subSiteTitle').val();

            hostweburl = decodeURIComponent(getQueryStringParameter("SPHostUrl"));
            appweburl = decodeURIComponent(getQueryStringParameter("SPAppWebUrl"));
            var scriptbase = hostweburl + "/_layouts/15/";
            $.getScript(scriptbase + "SP.RequestExecutor.js", execCrossDomainRequest);
            function execCrossDomainRequest() {
                var executor = new SP.RequestExecutor(appweburl);
                var queryUrl = appweburl + "/_api/SP.AppContextSite(@target)/web/webs?$select=Title,Url,WebTemplate&$filter=WebTemplate ne 'APP'&$where=Title.Contains=checkTextTypedIn&@target='" + hostweburl + "'";

                executor.executeAsync(
                     {
                         url: queryUrl,
                         method: "GET",
                         headers: { "Accept": "application/json; odata=verbose" },
                         success: successHandler,
                         error: errorHandler
                     }
                         );
            }
});

This is my input box var checkTextTypedIn = $('#subSiteTitle').val();

Here is am trying to se if title contains $where=Title.Contains=checkTextTypedIn its not working right now because i dont now how to write the where statement? Can someone maybe help me ?