C# Lambda .Contains() on multiple properties

We are using the following to generate a search query (using NHibernate).

GetAll(x => x.Username.ToUpper().Contains(SEARCH)).ToList();

Is it possible to do a search (Contains) for multiple properties, something like ...

    GetAll(x => x.Username.ToUpper().Contains(SEARCH) 
        && x => x.Firstname.ToUpper().Contains(SEARCH) 
        && x => x.Lastname.ToUpper().Contains(SEARCH)).ToList();

Using C#