using System;

using System.Linq;

using System.Xml;                   

using System.Xml.Linq;

using System.Collections; 

using System.Collections.Generic;

using System.Data;

using System.Data.DataSetExtensions;

using System.Data.Linq;

using System.Text;

using System.Text.RegularExpressions;

using System.Xml.Serialization; 

using System.IO;

using System.Globalization;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        var searchText = "duck";

        List<Person> persons = new List<Person>()

        {

            new Person() { FirstName = "Donald", LastName = "Duck", Company = "Disney" },

            new Person() { FirstName = "Daffey", LastName = "Duck", Company = "Warner Brothers" }

        };

        var splits = searchText.Trim().Split(new string[] {" "}, StringSplitOptions.RemoveEmptyEntries);

​

        var result = persons.Where(p=> splits.All(x=>  

                         p.FirstName.IndexOf(x, StringComparison.OrdinalIgnoreCase) >=0

                      || p.LastName.IndexOf(x, StringComparison.OrdinalIgnoreCase) >=0                                                

                      || p.Company.IndexOf(x, StringComparison.OrdinalIgnoreCase) >=0));

        result.Dump();

​

    }

}

​

public class Person

{

    public string FirstName;

    public string LastName;

    public string Company;

}

​