You can build an expression tree which contains a bitwise OR operation using Expression.Or method. For example, you have the following code.
bool value = true | false;
Console.WriteLine(value);
Here is the code that is required to build the same functionality using expression tree.
Expression greaterThanExpr = Expression.Or(
Expression.Constant(true),
Expression.Constant(false)
);
Console.WriteLine(Expression.Lambda<Func<bool>>(greaterThanExpr).Compile()());