Android: How to create a specific horizontal linear layout

I am making an app where there is a custom search bar. I want there to be a search part that is big, a spinner for region selection that is a small square, and a search button that is also a small square.

Here is what I am talking about.

The code I have right now is this:

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
xmlns:tools="http://ift.tt/LrGmb4" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    >


<EditText
    android:hint="@string/summoner_name"
    android:layout_width="wrap_content"
    android:layout_weight="75"
    android:layout_height="wrap_content"
    android:id="@+id/summoner_name"/>

    <Spinner
        android:layout_weight="1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/regions">

    </Spinner>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:id="@+id/search_button"/>


</LinearLayout>

However, this makes the search half the screen, and the button for 2/5's the screen, and the spinner for a smaller ammount. Anyone know how to accomplish this?

Thanks :)