mvc4 expression tree for contains integer - entity-framework

Question

I want to implement expression tree for integers as in below query:
Select * From TableName Where PKID In (1,2,3,4,5)
The relevant extracted code:
protected Expression<Func<T, bool>> GetExpression<T>(string propertyName, string propertyValue, string propertyType)
{
var parameter = Expression.Parameter(typeof(T), "type");
switch (propertyType)
{
case "string":
case "string?":
var stringProperty = Expression.Property(parameter, propertyName);
var stringValue = Expression.Constant(propertyValue.Trim(), typeof(string));
MethodInfo stringMethod = typeof(string).GetMethod("Contains", new[] { typeof(string) });
var stringContainsMethod = Expression.Call(stringProperty, stringMethod, stringValue);
return Expression.Lambda<Func<T, bool>>(stringContainsMethod, parameter);
case "int?":
var intProperty = Expression.Property(parameter, propertyName);
var intValues = Expression.Constant(propertyValue.Trim(), typeof(string));
MethodInfo intMethod = typeof(string).GetMethod("Contains", new[] { typeof(string) });
var intContainsMethod = Expression.Call(intProperty, intMethod, intValues); // this line gives error
return Expression.Lambda<Func<T, bool>>(intContainsMethod, parameter);
}
}
// Calling above function for string works. Products is a table in Database and Entity framework generated the class based on database first.
var filterLambda = GetExpression<Products>("ProductName", "chicken", "string?"); // No error here, works great
// Calling above function for int gives error
var filterLambda = GetExpression<Products>("ProductId", "1,2,3,4,5", "int?"); // Error here
I get error:
Method 'Boolean Contains(System.String)' declared on type 'System.String' cannot be called with instance of type 'System.Int32'
Of course it is pretty much clear that the column ProductId is integer and the value is string. Integer doesnt have contains so I thought I should use strings contains method. Please can any one tell me how do I solve this?