How to do a LIKE query in Arel and Rails?

I want to do something like:

SELECT * FROM USER WHERE NAME LIKE '%Smith%';

My attempt in Arel:

# params[:query] = 'Smith'
User.where("name like '%?%'", params[:query]).to_sql

However, this becomes:

SELECT * FROM USER WHERE NAME LIKE '%'Smith'%';

Arel wraps the query string 'Smith' correctly, but because this is a LIKE statement it doesnt work.

How does one do a LIKE query in Arel?

P.S. Bonus--I am actually trying to scan two fields on the table, both name and description, to see if there are any matches to the query. How would that work?

This is how you perform a like query in arel:

users = User.arel_table
User.where(users[:name].matches("%#{user_name}%"))

PS:

users = User.arel_table
query_string = "%#{params[query]}%"
param_matches_string =  ->(param){ 
  users[param].matches(query_string) 
} 
User.where(param_matches_string.(:name)\
                       .or(param_matches_string.(:description)))

Try

User.where("name like ?", "%#{params[:query]}%").to_sql

PS.

q = "%#{params[:query]}%"
User.where("name like ? or description like ?", q, q).to_sql

Aaand it's been a long time but @cgg5207 added a modification (mostly useful if you're going to search long-named or multiple long-named parameters or you're too lazy to type)

q = "%#{params[:query]}%"
User.where("name like :q or description like :q", :q => q).to_sql

or

User.where("name like :q or description like :q", :q => "%#{params[:query]}%").to_sql

Reuben Mallaby's answer can be shortened further to use parameter bindings:

User.where("name like :kw or description like :kw", :kw=>"%#{params[:query]}%").to_sql

Don't forget escape user input. You can use ActiveRecord::Base.sanitize_sql_like(w)

query = "%#{ActiveRecord::Base.sanitize_sql_like(params[:query])}%"
matcher = User.arel_table[:name].matches(query)
User.where(matcher)

You can simplify in models/user.rb

def self.name_like(word)
  where(arel_table[:name].matches("%#{sanitize_sql_like(word)}%"))
end