Using Arel and Scope to implement SQL "LIKE" statements

person.rb

class Person < ActiveRecord::Base
  scope :matches, lambda {|conditions|
    where conditions.map {|key, value|
      if value.is_a? Array
        value.map {|v| arel_table[key].matches("%#{v}%")}
      else
        arel_table[key].matches("%#{value}%")
      end
    }.flatten.inject(:or)
  }
end

#where last_name like "%Watts%"
persons = Person.matches(:last__name => "Watts")
#where last_name like "%Watts%" or last_name like "%Pena%"
persons = Person.matches(:last_name => ["Watts", "Pena"])
#where (last_name like "%Watts%" or last_name like "%Pena%") or first_name like "%Bob%"
persons = Person.matches(:last_name => ["Watts", "Pena"], :first_name => "Bob")
#Chainining with other conditions: where (email = 'foo@doamin.com)' and (last_name like "%Watts%" or last_name like "%Pena%")
persons = Person.where(:email => "foo@domain.com").matches(:last_name => ["Watts", "Pena"])

Arel provides very powerful capabilities in database query, but calling arel_table[] seems ugly.
I think it is better place Arel based conditions inside of ActiveRecord scopes so that it will make your controllers clean.