using System;

using System.Dynamic;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        dynamic line = new ExpandoObject();

        line.Filial = "";             

        line.Cidade = "";

        line.Cep = "";

        line.Uf = "";

        line.Cliente = "";              

        line.Cnpj = "";

        var fields = new List<string>() { "Cidade", "Cep", "Uf", "Cliente", "Cnpj", "Filial", "Algum" };

        var dicLine = (IDictionary<string, object>)line;

        foreach(var f in fields)

        {

            if (dicLine.ContainsKey(f))

            {

                dicLine[f] = "teste";

            }

        }

        Console.WriteLine("line.Cep=" + line.Cep);

    }

}