jQuery Ajax调用-读取数据

Im trying to read\map my object but cant see how im going wrong?

var model = { LastName: templastname, FirstName: tempfirstname, Mobile: tempmobile, AccountId: tempaccountId, Pin: tempPin }
$.ajax({
            url: "/Client/Get/",
            type: 'GET',
            data: $.param(model, true),
            cache: false,
            crossDomain: true,
            async: true,
            dataType: 'json',
            success: function (data) {

            },
            error: function (event) {

            },
            headers: {
                'Access-Control-Allow-Origin': '*'
            },
        });

Controller

 public JsonResult GetClient(string model)
        {
            var e = new ClientMapper();
            var objJavascript = new JavaScriptSerializer();

            e = objJavascript.Deserialize<ClientMapper>(model); <--Blows up
}

 private class ClientMapper
        {
            public string FirstName { get; set; }
            public string LastName { get; set; }
            public string AccountId { get; set; }
            public string Mobile { get; set; }
            public string Pin { get; set; }
        }

Model value:

LastName=dfdfdf&FirstName=dfdfdfdf&Mobile=dfdfdf&AccountId=4e82dbfe-2b7f-472c-b66c-0707b1d66ba2&Pin=1234&_=1469644529256

Any ideas how I format this correctly?

Instead of writing string model in function param write "ClientMapper" make that class public. C# Mvc will aumatically map the json to object

public class ClientMapper {....}
public JsonResult GetClient(ClentMapper model)