Possible solution

LinqExpression

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
using LinqKit;
using System.Text.RegularExpressions;

namespace DynamicQueryProblem
{
    public class PersonRepository
    {
        private FakeEntityModel _entities = new FakeEntityModel();

        /// <summary>
        /// Zoekmethode die aangeroepen word vanuit onze webpagina en de resultaten vervolgens 
        /// in de grid weergeeft
        /// </summary>
        /// <param name="query"></param>
        /// <returns></returns>
        public List<Person> Search(string query)
        {
            var keywords = query.ToLower().Split(' ');
            return Search(keywords);
        }

        public List<Person> Search(params string[] keywords)
        {
            //                 ____.                       _______                         
            //    |    | ____  __ ____  _  __  \      \ _____  _____    _____  
            //    |    |/  _ \|  |  \ \/ \/ /  /   |   \\__  \ \__  \  /     \ 
            //\__|    (  <_> )  |  /\     /  /    |    \/ __ \_/ __ \|  Y Y  \
            //\________|\____/|____/  \/\_/   \____|__  (____  (____  /__|_|  /
            //                                        \/     \/     \/      \/ 
            //___________    .__  .__  ___________.__.__  .__             .___
            //\_   _____/_ __|  | |  | \_   _____/|__|  | |  |   ____   __| _/
            // |    __)|  |  \  | |  |  |    __)  |  |  | |  | _/ __ \ / __ | 
            // |     \ |  |  /  |_|  |__|     \   |  |  |_|  |_\  ___// /_/ | 
            // \___  / |____/|____/____/\___  /   |__|____/____/\___  >____ | 
            //     \/                       \/                      \/     \/ 
            //___________.__             .____    .__               
            //\__    ___/|  |__   ____   |    |   |__| ____   ______
            //  |    |   |  |  \_/ __ \  |    |   |  |/    \ / ____/
            //  |    |   |   Y  \  ___/  |    |___|  |   |  < <_|  |
            //  |____|   |___|  /\___  > |_______ \__|___|  /\__   |
            //                \/     \/          \/       \/    |__|
            //   _____                   __                
            //  /     \ _____    _______/  |_  ___________ 
            // /  \ /  \\__  \  /  ___/\   __\/ __ \_  __ \
            // /    Y    \/ __ \_\___ \  |  | \  ___/|  | \/
            //\____|__  (____  /____  > |__|  \___  >__|   
            //        \/     \/     \/            \/       
            //________                          __   
            //\_____  \  __ __   ____   _______/  |_ 
            // /  / \  \|  |  \_/ __ \ /  ___/\   __\
            // /   \_/.  \  |  /\  ___/ \___ \  |  |  
            // \_____\ \_/____/  \___  >____  > |__|  
            //       \__>           \/     \/      
            var predicate = PredicateBuilder.True<Person>();
            var expressions = FullTextSearchExpressionForPerson(keywords);

            predicate = expressions.Aggregate(predicate, (current, exp) => current.And(exp));

            List<Person> searchresult = this.GetPersons(predicate);

            return searchresult;
        }

        protected Expression<Func<Person, bool>> FullTextSearchExpressionForPerson(string keyword)
        {
            var keywordCopy = keyword;

            return (p => p.Name.ToLower().Contains(keywordCopy) ||
                    p.Initials.ToLower().Contains(keywordCopy) ||
                    p.Address.ToLower().Contains(keywordCopy) ||
                    p.Remark.ToLower().Contains(keywordCopy));
        }

        protected IEnumerable<Expression<Func<Person, bool>>> FullTextSearchExpressionForPerson(string[] keywords)
        {
            foreach(var keyword in keywords)
            {
                var keywordCopy = keyword;

                yield return FullTextSearchExpressionForPerson(keywordCopy);
            }
        }

        public IQueryable<Person> Query()
        {
            return _entities.Persons;
        }

        public List<Person> GetPersons(Expression<Func<Person, bool>> predicate)
        {
            return _entities.Persons.Where(predicate).ToList();
        }
    }
}