LINQ to Entity cannot use System.Object.GetValue - entity-framework

Question

Below find a method that does not work. We fail on the line query.Select(...
Below that find a method with hard coded object property names which does work. But, this method is obviously not dynamic, nor flexible. There may be many properties of a Customer I may wish to search on.
The error string is at bottom. I get it that somehow the LINQ to Entity is unable to deal with conversion of GetValue to some sort of TSQL. Would anyone know of how I might code this up?
public List<Customer> GetForQuery(params Tuple<string, string>[] keyValuePairs) {
using (var db = new DBEntities()) {
var availableProperties = typeof(Customer).GetTypeInfo().DeclaredProperties.ToList();
var query = db.Customers.Select(c => c);
foreach (Tuple<string, string> pair in keyValuePairs) {
PropertyInfo pi = availableProperties.First(p => p.Name.Equals(pair.Item1));
if (pi == null)
continue;
query = query.Where(u => pi.GetValue(u, null).ToString().StartsWith(pair.Item2));
}
var results = query.Select(c => c).ToList();
return results;
}
}
How I might call the above:
CustomerController custController = new CustomerController();
List<Customer> results = custController.GetForQuery(Tuple.Create<string, string>("FName", "Bob" ));
The working fixed method:
public List<Customer> GetForQuery(string firstName = "", string lastName = "", string phoneNumber = "") {
using (var db = new DBEntities()) {
var query = db.Customers.Select(c => c);
if (firstName.HasContent())
query = query.Where(u => u.FName.StartsWith(firstName));
if (lastName.HasContent())
query = query.Where(u => u.LName.StartsWith(lastName));
if (phoneNumber.HasContent())
query = query.Where(u => u.EveningPhone.StartsWith(phoneNumber));
var results = query.Select(c => c).ToList();
return results;
}
}
ERROR:
LINQ to Entities does not recognize the method 'System.Object GetValue(System.Object, System.Object[])' method, and this method cannot be translated into a store expression.