How do I create a "magic shield"?

I want to create this shield that always appears in front of the player's torso, but I don't know how to always make it go a few studs away from the front of the player's torso.

Here's what I got :

local plr = script.Parent.Parent.Parent
local char = plr.Character or plr.CharacterAdded:Wait()
local p = Instance.new("Part",game.Workspace)
active = false
script.Parent.MouseButton1Click:Connect(function()
        if char and not active then
            local torso = char:WaitForChild("Torso")
            active = true
            p.Position = Vector3.new(torso.Position.X + 5,torso.Position.Y,torso.Position.Z)
            p.Anchored = true
            p.Size = Vector3.new(5,10,1)
            p.Transparency = .7
            p.Material = Enum.Material.Neon
            wait(10)
            p:Destroy()
            wait(12)
            active = false
        end
    end)