Something like this (in VB.NET) :
Dim filter As New PredicateExpression
Dim fld As New EntityField2("currDate", New DbFunctionCall("getdate()", Nothing))
filter.Add(New FieldCompareExpressionPredicate(AccountFields.CreatedOn, Nothing, ComparisonOperator.GreaterThan, New DbFunctionCall("getdate()", Nothing)))
filter.AddWithOr(New FieldBetweenPredicate(fld, Nothing, AccountFields.CreatedOn, AccountFields.ModifiedOn))
Regards,
Danny