Try using simply "CityName.Contains(@1)" this will convert to the proper lambda since its a method invocation on an accessible type.
something like:
var query =
db.Customers.
Where("CityName.Contains(@0) or CityName.Contains(@1)", "London", "USA")
http://www.albahari.com/nutshell/predicatebuilder.aspx
db.Update(item, i => new { i.Status, i.TrackingNumber, i.UpdatedAt });
[]_repository.Update(file, x => x.Data, x => x.Name);